Cargo ships are your cheapest paid option. I’ve yet to do it, but contact the shipping companies and see what their passenger policies are. There are also shipping agents who coordinate with those companies as intermediates.

There’s also the potential of crewing a small boat if you have any skills or show them you want to learn fast. I did a lot of sailing around Panama just by sitting in a marina at either side of the canal and chatting with people who are about to sail somewhere. The work was either poorly paid ($50-100 per day) or free in exchange for a bed and food. For transatlantic/transpacific sailing though, I don’t know if you’re going to find as many yachters as I did who were just sailing in the Caribbean. That’s also a fun option if you want to build those skills since they need a certain number of crew to even transit the canal and they’re all going somewhere after.

edit: And for the latter you’ll also have luck on boater forums. I can’t remember which I used, but there was a designated subforum where people would post if they have or want crew work specifically for linehandling.